Technical Field
The present disclosure relates to an electroluminescent display device integrated with image sensors, the display device in which any loss of the aperture ratio of pixels does not occur.
Description of the Related Art
Depending on a material of an emission layer, electroluminescent display devices are classified into inorganic light emitting display devices and organic light emitting display devices. An active matrix-type organic light emitting display device includes an Organic Light Emitting Diode (OLED) which is a self-emitting element, and has advantages such as a quick response time, high emission efficiency, excellent brightness, and a wide viewing angle.
An OLED in the organic light emitting display includes an anode, a cathode, and an organic compound layer. The organic compound layer includes a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, and an electron injection layer EIL. When a voltage is applied to the anode electrode and the cathode electrode, holes passing through the HTL and electrons passing through the ETL move into the EML to form excitons, causing the EML to emit visible light.
Efforts are being made to study a method of embedding an image sensor in a display device. The image sensor includes a plurality of photo sensors. Such a display device is usually implemented in a manner in which additional photo sensors are distributed within the pixel array. In this method, the photo sensors do not operate as pixels, and thus, this may result in a reduction in the aperture ratio of a pixel in the pixel array. In the case of a high resolution display device, the size of a pixel is reduced as much as an area occupied by a photo sensor. Therefore, in this case, it is difficult to design pixels and secure manufacturing process margin.